Tumors constantly shed cancer cells, yet only a few of these stray cells manage to survive and colonize distant organs. The rest succumb to the stress of the journey. HHMI Investigator Joan Massagué of Memorial Sloan-Kettering Cancer Center has found evidence that some breast cancer cells can turn on genes that increase their chances of survival, specifically in bone.

Massagué and his colleagues previously discovered that breast cancer cells expressing a set of genes called the Src response signature (SRS) were more likely to metastasize to the bone. Cells that expressed those genes were more sensitive to cell growth-promoting molecules—called cytokines—that are expressed by bone cells, the researchers reported August 29, 2013, in Cell.

“For any cancer cell, it’s dreadfully rough to survive in the body after leaving a tumor,” says Massagué. “These cells selected for being more responsive to cytokines might just have this tiny extra chance of surviving in bone. But when you’re talking about tens of thousands of cancer cells circulating in the body per day, that tiny extra chance is enough to change the odds of a metastatic tumor forming.”

Massagué is now testing drugs that affect the SRS pathway to see if they can block cancers from spreading to the bone.